Static immersion tests of potential injection pipe steels 42CrMo4, X20Cr13, X46Cr13, X35CrMo4, and X5CrNiCuNb16-4 at T = 60 °C and ambient pressure, as well as p = 100 bar were performed for 700–8000 h in a CO₂-saturated synthetic aquifer environment similar to CCS sites in the Northern German Basin (NGB). Corrosion rates at 100 bar are generally lower than at ambient pressure. The main corrosion products are FeCO₃ and FeOOH with surface and local corrosion phenomena directly related to the alloy composition and microstructure. The appropriate heat treatment enhances corrosion resistance. The lifetime reduction of X46Cr13, X5CrNiCuNb16-4, and duplex stainless steel X2CrNiMoN22-5-3 in a CCS environment is demonstrated in the in situ corrosion fatigue CF experiments (axial push-pull and rotation bending load, 60 °C, brine: Stuttgart Aquifer and NGB, flowing CO₂: 30 L/h, +/− applied potential). Insulating the test setup is necessary to gain reliable data. S-N plots, micrographic-, phase-, fractographic-, and surface analysis prove that the life expectancy of X2CrNiMoN22-5-3 in the axial cyclic load to failure is clearly related to the surface finish, applied stress amplitude, and stress mode. The horizontal grain attack within corrosion pit cavities, multiple fatigue cracks, and preferable deterioration of austenitic phase mainly cause fatigue failure. The CF life range increases significantly when a protective potential is applied.

“MAKING-OF” – SUCCESSFULLY PLANNING AND IMPLEMENTING PEER-TO-PEER LECTURE FILMS

To mitigate carbon dioxide emissions CO₂ is compressed and sequestrated into deep geological layers (Carbon Capture and Storage CCS). The corrosion of injection pipe steels is induced when the metal is in contact with CO₂ and at the same time the geological saline formation water. Stainless steels X35CrMo17 and X5CrNiCuNb16-4 with approximately 17% Cr show potential as injection pipes to engineer the Northern German Basin geological onshore CCS-site. Static laboratory experiments (T = 60 °C, p = 100 bar, 700–8000 h exposure time, aquifer water, CO₂-flow rate of 9 L/h) were conducted to evaluate corrosion kinetics. The anomalous surface corrosion phenomena were found to be independent of heat treatment prior to exposure. The corrosion process is described as a function of the atmosphere and diffusion process of ionic species to explain the precipitation mechanism and better estimate the reliability of these particular steels in a downhole CCS environment.

Rising air travel demand, airport capacity issues, and schedule disruptions form part of the challenges that aviation stakeholders have to face in the upcoming decades. Minimizing ground times is one of their recent objectives as extended ground times induce operational, economic, and environmental risks. The flow of ground operations has a high impact on the overall air transportation system. Therefore, the impact and risks of extended ground times in passenger air transport were thoroughly compared, weighed, and compared based on pre-selected individual literature sources. Several studies deliver solution approaches to reduce ground times. The turnaround especially is a key element of any flight operation and impacts the competitive advantage of airlines and airports. Next to infrastructural changes, technological advancements, and operational performance improvements, the cooperation of stakeholders is a measure to shorten ground times. Special focus lies on the improvement of boarding procedures. They are essential for passenger air transport and reducing ground times.